The review is complete. The findings file is written and the working tree is otherwise unchanged.

Outcome: no reproducible math, boundary or numerical-gap defect found. The file .imd-findings.json holds an empty findings list and a coverage record of 34 rows: all 28 listed entry points plus six invariants, every one marked holds with a one-line reason.

What I verified in my area

• Fee arithmetic in all four swap modes. Exact-input buy floors the fee from the specified input, exact-output buy and exact-output sell gross up with ceiling division, exact-input sell floors from the output. On the real PoolManager, fee divided by gross equals the basis-point rate within one wei in both currency orders at 3500, 201 and 200 bps. The base-fee precondition in Canvas.recordFee holds in every mode, so the 67/25/8 split and the decay premium to the pot are exact.
• Launch decay boundary. The rate is 3500 at 0 s, 201 at 1799 s and 200 from 1800 s. A 100 IMD buy at 1799 s produced fee 2.01, treasury 0.16 and pot 1.85, as the formula predicts.
• Accumulator math. Settlement happens before every ownership count change, per-season final accumulators keep old accrual claimable, and the remainder carry keeps whole-unit claims under artist fees. The only leak is the sub-unit remainder crossing a season boundary, at most 4095 scaled units or under 4e-21 IMD.
• Repaint pricing and windows. The price view and the paint path use the same expiry comparison, so a repaint at exactly 24 hours costs 1 drop and starts a new window. The cap at 2^10 and the 50-pixel batch bound hold.
• Auction arithmetic. Minimum raise is a ceiling 5 percent, escrow updates cannot underflow, the end extension cannot underflow, and rank-based remainder assignment makes claims sum exactly to bid plus pot, including the sole-occupant case.
• Casts and overflows. Every narrowing cast is bounded by construction or uses a checked SafeCast; no intermediate product can exceed uint256 for the accepted decimals range of 2 to 36.

Dust-level effects I chose not to report as findings because the validation gates demote them and they are self-inflicted: a 1-wei exact-output sell pays a 1-wei fee, and buys under 50 wei pay no fee. The push-payment refund in Seasons.bid can only be blocked by the external IMD issuer's blocklist, which the README already documents as an outside power.

Static-analysis leads in my area were all checked and none reproduced as a defect: the timestamp comparisons implement the specified windows, the encodePacked line builds SVG text rather than a hash, and the flagged uninitialized local is a zero-initialized fixed array.

I ran the existing 35 offline tests, which all pass, plus five scratch probes on the real PoolManager that I deleted afterwards since no finding needed a proof file.

The findings file is valid, every snippet matches its line, and all 28 entry points have a coverage row. Git status shows only the untracked, git-ignored findings file and scratch test; no repository file was changed.

Review complete. I audited the Access Control, Trust Gap and Asymmetry failure modes against all five contracts and wrote the result to .imd-findings.json.

What I found

• No critical, high or medium defects in the permission model. Every guard holds as intended: hook callbacks are manager-only and bound to the single factory-initialized pool, Canvas mutators are hook-only or Seasons-only, both unlock callbacks are hash-bound and manager-only, and the router pulls funds only from its caller. I traced the paired surfaces (paint/settle, endSeason/open, releasePot/rollPot, bid/finalize/claim, beforeSwap/afterSwap fee branches, router swap/callback direction logic) and found the writes and reads mirror each other correctly.
• Low: uncapped auction extension. A single bidder can self-outbid once every ten minutes at the deadline and keep a season auction open indefinitely, locking the frozen pot away from pixel owners. A scratch test shows 800 extensions hold it open over 5 days for about 1 IMD of outstanding bid. Delay only, not theft.
• Info: tx.origin paint attribution. Buys through third-party routers credit the origin EOA, so smart-account buyers via the Universal Router hand their paint to a signer or bundler, and any router that attaches hookData is rejected outright. This is what the brief asks for; recorded as a trust assumption.
• Info: external IMD powers. The live IMD token has an owner, a blocklist and a transfer gate. Push refunds in bid mean a blocked high bidder makes the auction un-outbiddable. Outside the project's control and already documented.

Verification done

• Full offline suite: 35 passed. Stateful invariants and the independent fuzz model pass on the current tree.
• Robinhood fork rehearsal re-run at block 83,184,213 against the real PoolManager and IMD: passed.
• IMD token inspected over RPC on chain 4663 to confirm its owner and blocklist selectors.

Not covered: the site and docs, which are outside the assigned contract-permission area.

Review complete. The findings file is written and all four cited snippets match the tree line for line.

Outcome: no critical, high or medium defects in the control flow of the hook, router, canvas or auction contracts. I traced every listed entry point from caller to final state, including the v4 delta semantics the hook relies on (fee taken on the specified side in beforeSwap, on the unspecified side in afterSwap, claims minted and burned so the hook's delta nets to zero), the accumulator settlement across season rollovers, the frozen-pot release path, and the escrow checks in the auction. The full suite passes locally (35 tests, fork suite skipped by design).

Findings written to .imd-findings.json:

• Low, auction stall. Seasons.bid accepts self-outbids, the first bid may be 1 wei, and each late bid adds ten minutes with no cap. A scratch test held auction 1 open for six days with 864 bids and about 23 IMD of refundable float, while finalize kept reverting. No funds are lost and season rollover is not blocked, so the impact is delayed artist payouts.
• Info, partial-fill reverts. IMD-specified swaps through third-party routers with a real price limit revert with PartialFill instead of partially filling. Documented design limitation, recorded with a concrete input.
• Info, metadata gas floor. tokenURI costs about 12.5M gas even for a one-pixel canvas because all 4,096 slots are read. The README's 35M RPC requirement therefore applies to every season, not only dense ones.
• Info, tx.origin fallback. Relayed or account-abstraction buys through other routers credit paint to the relayer. Mandated by the brief and documented, noted for the judge.

Coverage: all 28 entry points have a row, plus two invariant rows. Two entry points reference findings (Seasons.bid, PlaceHook.afterSwap); the rest hold. Nothing was left unreached.

Not verified: live Robinhood state (the fork suite is opt-in and I ran only the offline suite), the IMD token's transfer-restriction powers beyond what the README states, and browser rendering of the site beyond reading its logic and required links.

Review complete. The findings file is valid, both snippets match their cited lines, and all 28 entry points plus two invariants have coverage rows.

Outcome: the economics hold up. I traced the Economic Security, Invariant and Flow Gap checklists against the fee, paint, accumulator, season and auction flows and found no loss-of-funds defect. One low and one informational finding are recorded in .imd-findings.json.

What I verified in depth

• Hook fee math for all four swap modes in both currency orders against the vendored v4 Hooks.afterSwap delta signs. Each fee is minted as an ERC-6909 claim equal to the recorded fee, so payouts are always backed, and recordFee can never revert on the baseFee <= fee guard.
• The split: 67% and 8% of the 2% base, remainder and launch premium to the pot, artists' share to the pot when no pixel is occupied. Rounding dust is carried, so credited scaled units never exceed artist fees.
• The accumulator: settlement happens before owned counts change, old-season accounts settle against the frozen endpoint, and cross-season skips preserve earnings. The hook's ERC-6909 balance plus all payouts equals total fees.
• Seasons: the 7-day freeze, the unbid-pot rollover gate that forces the pot into season N+1, exact pot-plus-bid distribution by rank, escrow conservation, and the blank-season path.

Findings

• Low, Seasons.bid push refund. The real IMD token on chain 4663 exposes blocked(address) and transfersEnabled(). If the issuer blocks the current high bidder, every later bid reverts at the refund, the auction runs out with the stale bid, and artists lose the difference. Reproduced in test/scratch/BlockedBidder.t.sol: a 1 wei bid beats a refused 500 IMD raise. Pull-based refunds remove the dependency.
• Info, PlaceHook.afterSwap. Any non-empty hookData from a non-project router reverts instead of falling back to tx.origin as the brief states. No funds at risk.

Not defects, noted for the judge. Fee avoidance through a hookless pool, last-block pixel capture before a freeze or a large buy, and the 1 wei opening bid are all consequences of the specified "pixel war" rules rather than code errors. Exact-input buys that would partially fill revert by documented design.

Coverage gaps. I did not audit the site or the deployment tooling, and I did not run the Robinhood fork suite. No proof file was attached since nothing reached high severity.

Added failure-path, fuzz, metadata, and multi-season invariant tests under test/.

• forge build: passed.
• forge test: 56 passed, 0 failed, 1 opt-in fork skip.
• Invariants: 24,576 calls, zero unexpected reverts.
• Robinhood fork: passed at block 83,189,645.

No confirmed implementation defects found. All changes are confined to test/.